cfor.hs

import Data.IORef

for init cond inc block = do
    let loop = do
        res <- cond
        if res then
            do
                block
                inc
                loop
        else
            return ()
    init
    loop

main = do
    i <- newIORef (1)
    for
        (return ())
        (do
            i <- readIORef i
            return (i <= 100)
        )
        (do
            iv <- readIORef i
            writeIORef i (iv + 1)
        )
        (do
            iv <- readIORef i
            print iv
        )